This invention in general relates to a method and apparatus that is useful in gauging drilled threaded holes in order to determine whether they are properly made. In general, the apparatus comprises a plug that is driven into a thread hole that is to be tested and a torque monitor that displays the torque required to drive the plug into the threaded hole.
In modern production facilities, it is necessary to have a method for testing whether a newly-formed threaded hole has been properly made. With the modern emphasis on quality control, it is important that a production facility be able to quickly and accurately test that the threaded holes that have been formed in various machine parts are of proper depth, are not out of round, and are true. The prior art mainly relied on a go/no-go gauge that consisted of a threaded plug that was manually inserted into the threaded hole to be tested. The go/no-go gauge gets its name from its method of testing. The gauge would be turned into the threaded hole to be tested, and if the gauge would enter the hole easily without the manual operator having to apply undue torque, the operator would know that the hole being tested was proper. If, however, the manual operator could not get the test plug into the hole, or if the test plug entered far too easily and was sloppily received within the hole, or if the test plug required undue torque to get into the hole, the operator would know that the hole was improper and could reject that part.
These prior art methods are unsatisfactory for a variety of reasons. In general, they rely upon a manual operator's discretion as to whether or not the hole was proper. It was left up to the manual operator's discretion as to whether a hole may be too large, too big or what would constitute undue torque that would indicate that the threads were not true. In addition, with any hand-held item, there is the danger that the testing device itself was not being applied level with the part to be tested. If the testing device were being applied skewed from the part to be tested, a true hole could be rejected as being improper since the testing threads would be out of line from the tested threads. In addition, modern production facilities typically make great numbers of parts at any one time. It is desirable within modern production facilities that robotic devices be used for as many production steps as possible. The prior techniques required intensive manual attention and was thus inefficient and expensive.
It is an object of the present invention therefore to provide a blind hole thread testing apparatus and method that can give an objective indication of whether a tested hole is proper or not.
It is further an object of the present invention to provide a blind hole thread testing apparatus and method in which the testing apparatus is mounted so as to be constrained to be level with respect to the part that is being tested.
It is further an object of the present invention to provide a blind hole thread testing apparatus that can be entirely automated and which requires as few manual steps as possible. In addition to the above objectives, it is an object of the present invention to provide such a device that requires relatively few movable parts and is sturdy.